var gl = null;
let loadCache = {};
var Loader = {
    load(path, cb) {
        if (loadCache[path]) {
            cb && (cb(loadCache[path]));
        } else {
            let img = new Image();
            img.src = path;
            img.onload = function () {
                loadCache[path] = img;
                cb && cb(img);
            };
        }
    }
};